LI B, LAI Z H, WU J J,et al.Experimental investigation on fluid sensitivity of marine-continental transitional shale reservoirs in the Ordos Basin[J].Journal of Henan Polytechnic University(Natural Science) ,2026,45(5):166-176.

doi:10.16186/j.cnki.1673-9787.2024030075

Received:2024/03/27

Revised:2024/09/24

Published:2026-07-24

Experimental investigation on fluid sensitivity of marine-continental transitional shale reservoirs in the Ordos Basin

Li Bing1,2, Lai Zhehan3, Wu Jianjun1,2, Chen Mingjun3, Bai Kunsen1,2, Kang Yili3, Ning Xianyi3

1.Institute of Engineering Technology， Petro China Coalbed Methane Company Limited， Xi’an  710082， Shaanxi， China；2.China United Coalbed Methane National Engineering Research Center Co.， Ltd.， Beijing  100095， China；3.State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation， Southwest Petroleum University， Chengdu  610500， Sichuan， China

Abstract:In the process of well construction and hydraulic fracturing in marine-continental transitional shale gas reservoir， fluid sensitivity damage is easily induced by the intrusion of drilling and completion fluids， which restricts gas well production. Marine-continental transitional shale gas reservoirs are characterized by diverse mineral types， high clay mineral content， large lithological variations， and poor pore connectivity， making their fluid sensitivity more complex. To systematically reveal the development patterns of fluid sensitivity in marine-continental transitional shale reservoirs and their dominant geological controls， experimental research on fluid sensitivity was carried out. Methods The marine-continental transitional shale gas reservoir in Member 2 of the Shanxi Formation on the eastern margin of the Ordos Basin was taken as the research object. On the basis of mineral composition and pore structure evaluation， shale samples with different fracture development degrees were drilled. Fluid sensitivity tests of fractures and matrix were designed and carried out by the high back pressure steady-state method and the pressure decay method. Results The results show that： （1）the fluid sensitivity of marine-continental transitional shale in the study area ranges from moderately strong to strong. The high clay mineral content is the main factor leading to severe fluid sensitivity damage； （2） the relatively high content of kaolinite and illite/smectite mixed-layer minerals is the main reason for the difference in fluid sensitivity between marine and marine-continental transitional shales； （3） the lithology of marine-continental transitional shale gas reservoir varies greatly， which aggravates the degree of fluid sensitivity damage caused by the intrusion of drilling and completion fluids and fracturing fluids.  Conclusions Based on the characteristic analysis and fluid sensitivity evaluation results of marine-continental transitional shale gas reservoirs， this paper proposes corresponding formation damage control measures. These can provide a scientific basis for optimizing the formulation and dosage of drilling and completion fluids and fracturing fluids， as well as for developing targeted moderate fracturing technologies.

Key words:marine-continental transitional shale;formation damage control;fluid sensitivity;permeability;clay minerals